Engine test method and apparatus

ABSTRACT

An engine is tested by deriving a first digital signal representative of a first engine parameter and a second digital signal representative of a second engine parameter. These signals provide inputs to a semi-conductor matrix which produces a digital output signal determined by the values of the input signals, the output signal being used to control an engine characteristic. The selections within the matrix are chosen for each combination of input signal so that for each combination of input signals, the output signal exercises the required control of the engine characteristic.

United States Patent 1 1 1111 3,745,817

Williams et al. 14 1 Jul I7, 1973 ENGINE TEST METHOD AND APPARATUS [56]References Cited [75] Inventors: Malcolm Williams, Solihull; UNITEDSTATES PATENTS Duncan Barry Hodgson, Whitnash, 3,319,613 5 1967 Begleyet al. 123 32 EA both of England 3,272,187 9/1966 Westbrook et al. 12332 EA [733] Assignee: Jose h Lucas (Industries) Limited,

Bimfingham, England Primary Examiner-Jerry W. Myracle Att0rney-l-lolman& Stern [22] Filed: Nov. 9, 1971 21 Appl. No.: 196,954 [571 ABSTRACT Anengine is tested by deriving a first digital signal rep- [3()] F i A liti P i it D t resentative of a first engine parameter and a seconddigital signal representative of a second engine parame- Nov. ll, 1970Great Britain ..53546/70 ter. These signals provide inputs to asemi-conductor matrix which produces a digital output signal deter- U-S-Cl. 17.3, A mined the values of the input ignals the output ig- [5 1]Int. Cl. G0lm 15/00 nal being used to control an engine characteristic,The Field of Search 119 1 selections within the matrix are chosen foreach combil23/32 EA nation of input signal so that for each combinationof input signals, the output signal exercises the required control ofthe engine characteristic.

2 Claims, 1 Drawing Figure ENGINE TEST METHOD AND APPARATUS Thisinvention relates to engine control systems of the kind in which any twoof three engine parameters, namely engine speed, manifold pressure(which can of course be a negative pressure) and throttle angle are usedto provide two signals, the signals providing inputs to a diode or othersuitable semi-conductor matrix, the matrix being designed to give anoutput determined by both input signals and this output being used tocontrol an engine characteristic. The invention is particularlyconcerned with control systems for engines used in road vehicles and inmost cases the engine characteristics controlled by the system is theinjection of fuel to the engine, although, where the engine has a sparkignition system, the ignition timing or a combination of the timing andfuel injection could be controlled.

The object of the invention is to provide a convenient method of testingan engine which facilitates the manufacture of a control system of thekind specified.

The invention further resides in a method of testing an enginecomprising deriving a first digital signal representative of a firstengine parameter and a second digital signal representative of a secondengine parameter, each of said signals providing an input to asemiconductor matrix which produces a digital output signal determinedby the values of the input signals, said output signal being used tocontrol an engine characteristic, and selecting the connections withinthe matrix for each combination of input signals so that, for eachcombination of the first and second digital signals, said output signalexercises the required control of said engine characteristic.

Preferably, said matrix is a diode matrix in which the diodes aredetachable so that the positions of the diodes within the matrix can bealtered so as to vary the connections within the matrix.

The invention further resides in apparatus for performing the method.

The accompanying drawing is a diagrammatic illustration of a device foruse in the manufacture of a fuel injection control system according toone example of the invention.

Referring to the drawing, there is provided a transducer 8 whichproduces an electrical signal representing the throttle angle of theengine with which the system is employed. The electrical signal from thetransducer 8 .is in the form of a 3 bit binary word which is fed tocontrol means 11 which serves to energise one of 8input lines 134 to13h, the input lines 13a to 13h fonning part of a diode matrix unit 10,the construction of which will be described later. The unit 10 furtherincludes 8 sets of input lines 16a to 16h, each of the lines 13a to 13hcrossing each of the sets of lines 16a to 16h. Although in the exampleshown there are 8 input lines 13 and 8 sets of lines 16, it will beappreciated that the number of lines can be more or less than thisfigure. Moreover, although in the example shown each set of lines 16contains 5 lines, they can be more or less lines in each set 16.

There is further provided a second transducer 9 which produces anelectrical signal representing engine speed, the signal being in theform of a 3 bit binary word which is fed to control means 12, whichenergises one of a set of lines 14a to 14h. The lines 14a to 14h areconnected to a switching device 15 having 8 sets of switches 15a to 15krespectively. The arrangement is suchthat when a signal appears on theline 14a, the

switches 15a connect the lines 16a to 5 output lines 21 coupled to adecoder 22, the output from which is fed to injection means 23controlling the quantity of fuel supplied to the engine.

The lines 16 and 13 are interconnected by diodes in a manner to bedescribed. In the drawing, the connections between the first two sets oflines 16a and 16b and the lines 13 are shown, each dot representing adiode connection. Suppose that the value of throttle angle is such thatthe line 13a is energised, and the engine speed is such that the line14a is energised, then the switches 15a connect the lines 16a to thedecoder 22, and the decoder 22 will receive a signal of the form 10,000,where 1 represents the diode connection between the line 13a and thefirst of the set of lines 16a. If the parameters now change in such amanner that the line 13g and the line 14b are energised, then thedecoder 22 will receive a signal 01,111. Thus, it will be appreciatedthat the unit 10'produces an output dependent on the two input signalscontrolled by the decoders, and controls the fuel in accordance with theconnections within the unit 10.

The unit 10 includes a base plate in the form of a peg board 31 abovewhich the lines 13 and 16 are supported by pegs (not shown). The lines13 extend in a first plane above the board 31, the lines 16 extend in asecond plane above the board 31 and at right angles to the lines 13.Each of the lines 13 crosses each of the lines 16 but is spaced from thelines 16. The design of the unit 10 is such that any line 13 can beconnected to any line 16' by one of a number of semi-conductor diodeseach of which can be detachably engaged between a line 13 and a line 16to electrically connect the lines. In the drawing, which illustrates thedevice in use, a number of diodes are shown connected between the lines13 and the first two groups of lines 16, the diode connections beingindicated by the dots previously referred to. During the manufacture ofan engine control system, the engine speed and the throttle angle of theengine are set at predetermined values such that the line 13a isenergised andthe line 14a is energised, energisation of the line 14aserving to couple the lines 16a to the output lines 21. The line 13a isconnected to the lines 16a by l or more diodes which may be chosenarbitrarily, or with some prior knowledge of the engine characteristic,and as shown the output lines 21 will receive a signal 10,000. Thesignal on the output lines 21 serves through the decoder'22 and theinjection means 23 to govern the amount of fuel supplied to the enginefor the predetermined throttle setting and engine speed, and theperfonnance of the engine under these circumstances is inspected. Thenature of the inspection dependson the intention of the designer, and byway of example the intention could be to maximise engine performance, orto minimise exhaust pollution.

When the engine characteristic has been inspected, the designer thenattempts to improve the situation by varying the diode connections. Itwill of course be appreciated that the connections chosen may notprovide the required results, and the next step may, merely by way ofexample, be to insert another diode at the connection of the line 13a tothe line so that the lines 21 receive a signal 1 1,000. This processcontinues until the optimum engine condition is reached. The enginespeed is then kept constant, but the throttle angle changed so that theline 13b is energised instead of the line 13a. The diode connectionsbetween the line 13b and the lines 160 are then varied in the same wayto give the best possible result. This procedure continues with all thesites in the matrix, the term site" being used to indicate the positionat which a line 13 can be connected by up to 5 diodes to a set of lines16.

It will of course be appreciated that once the required diode positionshave been found in the manner described, then diode matrix units can bemanufactured on a production basis for use in engine control systems.

The arrangement described above, whereby the diode connections are allfound empirically, is somewhat time consuming if the designer has noidea of the most likely diode connections at any given site. Inpractice, the designer may well be aware of the approximate connectionswhich will be needed, and so not every possible combination of diodes atevery site has to be attempted, so that the overall length of time takento select the diode connections is less than appears. However, in somecircumstances the designer may not have any advance informationwhatsoever, and in such a case it is possible to reduce the time takento select the diode positions in the following manner. The engine speedand the throttle angle are varied as before so that the site where theline 13a crosses the line 16a is inspected. However, the lines 21 aredisconnected from the switches 15, and are connected instead through 5manually operable switches respectively to a power source. Closing ofone of the 5 manually operable switches feeds a signal 1 to the decoder22, and in this way the decoder 22 can be fed with a digital signalwhich simulates the insertion of diodes into the unit 10. It is farquicker for an operator to manipulate the switches than to insert thediodes in the matrix unit, and when the manipulation of the switches iscompleted to give the best possible result, then the diodes are insertedat the appropriate site on the unit in accordance with the positions ofthe switches, so that if the first three switches are closed and thelast two are open, diodes are inserted to connect the line 13a to thefirst three of the lines 160, but not to the last two of the lines 16a.This action is repeated for each site, and considerably reduces the timenecessary for establishing the diode positions. It is necessary afterfinding the diode positions with the switches to insert the diodes inthe unit itself and then to repeat the tests, in case some of the diodesneed to be moved. During the repeat test, by virtue of the prevailingdynamic conditions when the engine is used in conjunction with the unit10 the switches can again be used instead of the diodes, as long as thediode connections are all present, and the lines 21 are coupled to theswitches 15 or to the manually operable switches at any given instant.

We claim:

1. A method of testing an engine comprising deriving a first set ofdigital signals representative of a range of values of a first engineparameter and a second set of digital signals representative of a rangeof values of a second engine parameter, feeding one signal from thefirst set representing one value of the first engine parameter and onesignal from the second set representing one value of the second engineparameter to a semiconductor matrix which produces a digital outputsignal determined by the values of the signals fed to the semi-conductormatrix, said output signal being used to control an enginecharacteristic, and selecting the connections within the matrix for saidcombination of one of the first set of digital signals and one of thesecond set of digital signals so that, said output signal exercises therequired control of said engine characteristics, and then repeating saidprocess for each possible combination of signals from the first set andthe second set.

2. Apparatus for testing an engine comprising in combination a firsttransducer for deriving a first digital signal having one of a pluralityof values representing a range of values of a first engine parameter, asecond transducer for deriving a second digital signal having one of aplurality of values representative of a range of values of a secondengine parameter, a diode matrix to which the signals from saidtransducers are applied, said diode matrix incorporating detachablediodes so that the positions of the diodes within the matrix can bealtered so as to vary the connections within the matrix, and enginecontrol means operable by the output from the diode matrix to controlsaid engine characteristic. i t =8

1. A method of testing an engine comprising deriving a first set ofdigital signals representative of a range of values of a first engineparameter and a second set of digital signals representative of a rangeof values of a second engine parameter, feeding one signal from thefirst set representing one value of the first engine parameter and onesignal from the second set representing one value of the second engineparameter to a semiconductor matrix which produces a digital outputsignal determined by the values of the signals fed to the semi-conductormatrix, said output signal being used to control an enginecharacteristic, and selecting the connections within the matrix for saidcombination of one of the first set of digital signaLs and one of thesecond set of digital signals so that, said output signal exercises therequired control of said engine characteristics, and then repeating saidprocess for each possible combination of signals from the first set andthe second set.
 2. Apparatus for testing an engine comprising incombination a first transducer for deriving a first digital signalhaving one of a plurality of values representing a range of values of afirst engine parameter, a second transducer for deriving a seconddigital signal having one of a plurality of values representative of arange of values of a second engine parameter, a diode matrix to whichthe signals from said transducers are applied, said diode matrixincorporating detachable diodes so that the positions of the diodeswithin the matrix can be altered so as to vary the connections withinthe matrix, and engine control means operable by the output from thediode matrix to control said engine characteristic.